Geodetic Instrumentation for Use on Machine Bored Tunnels

As advance rates of TBM bored tunnels increase, it is essential that all aspects of the control of the machine and the tunnel support are able to operate at the desired rate. This paper describes the innovative ways that the basic guidance system has been adapted to cater for the TBM’s that are currently in use used on the Gotthard tunnel where the traditional line of sight throughout the backup gear is continuously obstructed due to the use of a sprayed concrete support facility to the use. The guidance system utilizes features from the well proven system for distance and curved pipejacking applications where the main reference is attached to the moving pipe (tunnel lining). Accurate steering of the tunnelling machine is essential if the segmental lining is to be efficiently installed. The use of ring sequencing software for the determination of the ring type and rotation, significantly aids the rapid placement of the most appropriate ring, which in turn can be monitored for any immediate convergence with the innovative chained inclinometer convergence measurement system. All of this information together with the surface mapping, geotechnical, and surface monitoring data bases can be fully integrated with the monitoring of the machines operating parameters in the Controlled Boring Process software integration package to give the machine operator a complete graphical display of all that is happening around him, to ensure optimum control and speed of safe advance